An active noise reduction system, also known as active noise cancellation/control (ANC) system, generally use a microphone to pick up an acoustic error signal (also called a “residual” signal) after the noise reduction, and feeds this error signal back to an ANC filter. This type of ANC system is called a feedback ANC system. The ANC filter in a feedback ANC system is typically configured to reverse the phase of the error feedback signal and may also be configured to integrate the error feedback signal, equalize the frequency response, and/or to match or minimize the delay. Thus, the quality of a feedback ANC system heavily depends on the quality of the ANC filter. The same problem arises with ANC systems having a so-called feedforward or other suitable noise reducing structure. A feedforward ANC system generates by means of an ANC filter a signal (secondary noise) that is equal to a disturbance signal (primary noise) in amplitude and frequency, but has opposite phase. Thus, there is a general need for providing ANC systems with an improved performance.